1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Copyright (C) 2004-2013 Synopsys, Inc. (www.synopsys.com)
4  *
5  * MDIO implementation for ARC EMAC
6  */
7 
8 #include <linux/delay.h>
9 #include <linux/of_mdio.h>
10 #include <linux/platform_device.h>
11 #include <linux/gpio/consumer.h>
12 
13 #include "emac.h"
14 
15 /* Number of seconds we wait for "MDIO complete" flag to appear */
16 #define ARC_MDIO_COMPLETE_POLL_COUNT	1
17 
18 /**
19  * arc_mdio_complete_wait - Waits until MDIO transaction is completed.
20  * @priv:	Pointer to ARC EMAC private data structure.
21  *
22  * returns:	0 on success, -ETIMEDOUT on a timeout.
23  */
24 static int arc_mdio_complete_wait(struct arc_emac_priv *priv)
25 {
26 	unsigned int i;
27 
28 	for (i = 0; i < ARC_MDIO_COMPLETE_POLL_COUNT * 40; i++) {
29 		unsigned int status = arc_reg_get(priv, R_STATUS);
30 
31 		status &= MDIO_MASK;
32 
33 		if (status) {
34 			/* Reset "MDIO complete" flag */
35 			arc_reg_set(priv, R_STATUS, status);
36 			return 0;
37 		}
38 
39 		msleep(25);
40 	}
41 
42 	return -ETIMEDOUT;
43 }
44 
45 /**
46  * arc_mdio_read - MDIO interface read function.
47  * @bus:	Pointer to MII bus structure.
48  * @phy_addr:	Address of the PHY device.
49  * @reg_num:	PHY register to read.
50  *
51  * returns:	The register contents on success, -ETIMEDOUT on a timeout.
52  *
53  * Reads the contents of the requested register from the requested PHY
54  * address.
55  */
56 static int arc_mdio_read(struct mii_bus *bus, int phy_addr, int reg_num)
57 {
58 	struct arc_emac_priv *priv = bus->priv;
59 	unsigned int value;
60 	int error;
61 
62 	arc_reg_set(priv, R_MDIO,
63 		    0x60020000 | (phy_addr << 23) | (reg_num << 18));
64 
65 	error = arc_mdio_complete_wait(priv);
66 	if (error < 0)
67 		return error;
68 
69 	value = arc_reg_get(priv, R_MDIO) & 0xffff;
70 
71 	dev_dbg(priv->dev, "arc_mdio_read(phy_addr=%i, reg_num=%x) = %x\n",
72 		phy_addr, reg_num, value);
73 
74 	return value;
75 }
76 
77 /**
78  * arc_mdio_write - MDIO interface write function.
79  * @bus:	Pointer to MII bus structure.
80  * @phy_addr:	Address of the PHY device.
81  * @reg_num:	PHY register to write to.
82  * @value:	Value to be written into the register.
83  *
84  * returns:	0 on success, -ETIMEDOUT on a timeout.
85  *
86  * Writes the value to the requested register.
87  */
88 static int arc_mdio_write(struct mii_bus *bus, int phy_addr,
89 			  int reg_num, u16 value)
90 {
91 	struct arc_emac_priv *priv = bus->priv;
92 
93 	dev_dbg(priv->dev,
94 		"arc_mdio_write(phy_addr=%i, reg_num=%x, value=%x)\n",
95 		phy_addr, reg_num, value);
96 
97 	arc_reg_set(priv, R_MDIO,
98 		    0x50020000 | (phy_addr << 23) | (reg_num << 18) | value);
99 
100 	return arc_mdio_complete_wait(priv);
101 }
102 
103 /**
104  * arc_mdio_reset
105  * @bus: points to the mii_bus structure
106  * Description: reset the MII bus
107  */
108 static int arc_mdio_reset(struct mii_bus *bus)
109 {
110 	struct arc_emac_priv *priv = bus->priv;
111 	struct arc_emac_mdio_bus_data *data = &priv->bus_data;
112 
113 	if (data->reset_gpio) {
114 		gpiod_set_value_cansleep(data->reset_gpio, 1);
115 		msleep(data->msec);
116 		gpiod_set_value_cansleep(data->reset_gpio, 0);
117 	}
118 
119 	return 0;
120 }
121 
122 /**
123  * arc_mdio_probe - MDIO probe function.
124  * @priv:	Pointer to ARC EMAC private data structure.
125  *
126  * returns:	0 on success, -ENOMEM when mdiobus_alloc
127  * (to allocate memory for MII bus structure) fails.
128  *
129  * Sets up and registers the MDIO interface.
130  */
131 int arc_mdio_probe(struct arc_emac_priv *priv)
132 {
133 	struct arc_emac_mdio_bus_data *data = &priv->bus_data;
134 	struct device_node *np = priv->dev->of_node;
135 	struct mii_bus *bus;
136 	int error;
137 
138 	bus = mdiobus_alloc();
139 	if (!bus)
140 		return -ENOMEM;
141 
142 	priv->bus = bus;
143 	bus->priv = priv;
144 	bus->parent = priv->dev;
145 	bus->name = "Synopsys MII Bus";
146 	bus->read = &arc_mdio_read;
147 	bus->write = &arc_mdio_write;
148 	bus->reset = &arc_mdio_reset;
149 
150 	/* optional reset-related properties */
151 	data->reset_gpio = devm_gpiod_get_optional(priv->dev, "phy-reset",
152 						   GPIOD_OUT_LOW);
153 	if (IS_ERR(data->reset_gpio)) {
154 		error = PTR_ERR(data->reset_gpio);
155 		dev_err(priv->dev, "Failed to request gpio: %d\n", error);
156 		mdiobus_free(bus);
157 		return error;
158 	}
159 
160 	of_property_read_u32(np, "phy-reset-duration", &data->msec);
161 	/* A sane reset duration should not be longer than 1s */
162 	if (data->msec > 1000)
163 		data->msec = 1;
164 
165 	snprintf(bus->id, MII_BUS_ID_SIZE, "%s", bus->name);
166 
167 	error = of_mdiobus_register(bus, priv->dev->of_node);
168 	if (error) {
169 		dev_err(priv->dev, "cannot register MDIO bus %s\n", bus->name);
170 		mdiobus_free(bus);
171 		return error;
172 	}
173 
174 	return 0;
175 }
176 
177 /**
178  * arc_mdio_remove - MDIO remove function.
179  * @priv:	Pointer to ARC EMAC private data structure.
180  *
181  * Unregisters the MDIO and frees any associate memory for MII bus.
182  */
183 int arc_mdio_remove(struct arc_emac_priv *priv)
184 {
185 	mdiobus_unregister(priv->bus);
186 	mdiobus_free(priv->bus);
187 	priv->bus = NULL;
188 
189 	return 0;
190 }
191